There's a reason why new coneflower cultivars cost more than older cultivars, said a University of Illinois Extension horticulture educator.

"To produce enough plants to meet the market's demand for the new cultivars, the plants are propagated in labs via tissue culture," explained Jennifer Schultz Nelson. "Tissue culture takes a piece of the plant and using plant hormones in a dish or flask, produces thousands of tiny new plants.

"These are grown and sold to the public. This requires more resources than dividing existing plants. This at least partially explains why new coneflower cultivars cost more."

Coneflowers are tough little native plants that have adapted to a wide range of environments across North America. Their genus name, Echinacea, comes from the Latin name for hedgehog, echinos, referring to the often prickly lower stem of the plant.

"They all have the same general form--very upright plants two to four feet in height, dark green foliage topped with showy flowers," said Nelson. "They are fast-growers and self-sow their seed profusely."

Four species are common in the United States. Echinacea angustifolia, Narrow-leaf Purple Coneflower, is native to the western United States. Echinacea pallida, Pale Coneflower, is from the central United Sates and has been used by Native Americans medicinally for bites, stings, and burns. Echinacea paradoxa, Yellow Coneflower, is native specifically to the Ozark Mountains. Echinacea purpurea, Purple Coneflower, is native to the central United States and is probably the species most familiar to Illinois residents.

The genus Echinacea is part of the Aster family. Plants in this family have daisy-like flowers, which are technically composed of two types of flowers. The showy petals are called ray flowers, and the center of the flower is made up of much smaller disk flowers. In coneflower, only the center disk flowers are fertile and can set seed.

"Coneflowers are also self-incompatible, meaning they cannot pollinate their own flowers," Nelson explained. "They depend on insects like bees to transfer pollen between plants for successful seed set. Strangely enough, this pollen can be from any other coneflower, not just the same species."

In 1968, Ronald McGregor published an article detailing how different species of the plant could be successfully crossed. At the time, no one paid much attention and the article lay unnoticed until 1995. Then, Jim Ault, director of ornamental plant research at the Chicago Botanic Garden, selected the plant to be featured in a new plant breeding initiative at the Botanic Garden.

"Ault concluded after reading McGregor's article that there was an untapped genetic goldmine waiting within the genus Echinacea," she said. "He spent two years assembling a collection of Echinacea species and cultivars. By 1997, he began crossing his different coneflowers, focusing on interspecific crosses, or crosses between different coneflower species."

But he is not the only one experimenting with the plant. In recent years, a flood of new Echinacea colors have shown up in garden centers. Counting the original purple and white cultivars, there are over 30 cultivars now available.

"Some are quite unique, like 'Doppelganger' also known as 'Doubledecker,' that has a second layer of petals at the center of the flower resembling a crown," Nelson said. "Some, like 'Little Giant' are fragrant. The possibilities seem endless."

A frequent question is where seed for these new cultivars can be purchased.

"The simple answer is, you can't buy it," she explained. "The longer answer is these novel cultivars come from progeny of a specific cross. There may have been one usable plant amid thousands of duds. So, we use tissue culture to generate new plants, which is much quicker than waiting to divide plants but may cost more."